Instruction Manual

Chapter 3 Hardware
38 Reference Manual ETX-PVR
SMBus
The I/O Hub contains an integrated SMBus controller with both a host and slave SMBus port; but the host
cannot access the slave internally. The slave port allows an external master access to the I/O Hub through the
J4 connector. The master contained in the I/O Hub is used to communicate with the SODIMM SPD (Serial
Presence Detect), Temperature Sensor, and the clock generator. Table 3-7 lists the addresses for these
devices with the components and corresponding binary addresses of the SMBus.
Table 3-8 describes the pin signals of the ETX-PVR X4 ETX interface connector.
Table 3-7. SMBus Reserved Addresses
Matrix Component Address Binary
SODIMM SPD 1010,000x
b
Clock Generator 1101,001x
b
Temperature Sensor 1001,100x
b
Table 3-8. Complete X4 Interface Pin Signal Descriptions (J4)
J4
Pin
#
Signal Description
1, 2
GND Ground
3 5V_SB 5 volt Suspend – This control signal is sent to the ATX power supply for a
suspended or standby state.
4PWGIN
Power Good In – This active high input signal indicates to the ETX-PVR the
power is good, and it can begin the boot process.
5 PS_ON Power Supply On – This active low output signal from the ETX-PVR is sent
to the ATX power supply to turn it on.
6 SPEAKER Speaker – This PC speaker output signal must be connected to a speaker
(piezoelectric or dynamic) on the baseboard to hear the output (beeps).
7 PWRBTN* Power Button – This signal provides a ground temporally through an open
collector driver to the ATX power supply to change states (turn it on).
8 BATT Battery Voltage – This is the + battery connection to baseboard for +3 volt
lithium backup battery used for RTC operation and CMOS non-volatile
memory.
9 NC Not Connected
10 LILED Link Integrity LED – The LINK LED pin indicates link integrity. If the link is
valid in either 10 or 100Mbps, the LED is on; if the link is invalid, the LED is
off.
11 RSMRST* Resume Reset – This signal is driven low by external circuitry to reset the
power management logic on the ETX-PVR.
12 ACTLED Activity LED – The Activity LED pin indicates either transmit or receive
activity. When activity is present, the activity LED is on; when no activity is
present, the activity LED is off.
13 NC Not Connected
14 SPDLED Speed LED – The speed LED pin indicates the speed. The speed LED will be
on at 100 Mbps and off at 10 Mbps.
15 NC Not Connected
16
I
2
CLK This clock line implements an I
2
C bus, which supports external slave devices
only. The I
2
C interface supports EEPROMs and other simple I/O devices.